title: Metagenomic screening for aromatic compound-responsive transcriptional regulators.
abstract: We applied a metagenomics approach to screen for transcriptional regulators that sense aromatic compounds. The library was constructed by cloning environmental DNA fragments into a promoter-less vector containing green fluorescence protein. Fluorescence-based screening was then performed in the presence of various aromatic compounds. A total of 12 clones were isolated that fluoresced in response to salicylate, 3-methyl catechol, 4-chlorocatechol and chlorohydroquinone. Sequence analysis revealed at least 1 putative transcriptional regulator, excluding 1 clone (CHLO8F). Deletion analysis identified compound-specific transcriptional regulators; namely, 8 LysR-types, 2 two-component-types and 1 AraC-type. Of these, 9 representative clones were selected and their reaction specificities to 18 aromatic compounds were investigated. Overall, our transcriptional regulators were functionally diverse in terms of both specificity and induction rates. LysR- and AraC- type regulators had relatively narrow specificities with high induction rates (5-50 fold), whereas two-component-types had wide specificities with low induction rates (3 fold). Numerous transcriptional regulators have been deposited in sequence databases, but their functions remain largely unknown. Thus, our results add valuable information regarding the sequence-function relationship of transcriptional regulators.
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Uchiyama
authors.forename: Kentaro
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D001419:Bacteria / Q000235:genetics*; D001483:Base Sequence; D002396:Catechols; D003001:Cloning, Molecular; D004926:Escherichia coli; D015723:Gene Library; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D006841:Hydrocarbons, Aromatic / Q000633:toxicity*; D006873:Hydroquinones; D054892:Metagenome / Q000235:genetics*; D056186:Metagenomics; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D050436:Regulatory Elements, Transcriptional / Q000187:drug effects* / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D002396:Catechols; D006841:Hydrocarbons, Aromatic; D006873:Hydroquinones; C031136:3-methylcatechol; D049452:Green Fluorescent Proteins; C038861:4-chlorocatechol; C031927:hydroquinone